1. Field
The following description relates to backlight units and display devices including backlight units, and more particularly, to backlight units that provide collimated light.
2. Description of the Related Art
Backlight units (BLU) may supply light in liquid crystal display devices. However, backlight units may not be self-emitting devices.
A general backlight unit emits radially spreading light, that is, Lambertian light, to a liquid crystal layer. Thus, luminance and colors of light that vary according to viewing angles, due to various lengths of an optical path of light that passes through the liquid crystal layer, need to be compensated for to produce a clear image for a user. On the other hand, in a collimation backlight unit that provides collimated light, a length of an optical path of light that passes through a liquid crystal layer does not significantly change, and thus luminance and color compensation characteristics of light are improved.
By providing collimated light in a backlight unit and forming a diffuser on a liquid crystal panel, a viewing angle may be presented.
In addition, three-dimensional (3D) displays may also require collimated light according to the configuration of systems. For example, a high-density directional (HDD) display, integral imaging, and holography each typically requires collimated light. Highly collimated light generally improves the performance of systems or simplifies the design of systems.